Doing issue advocacy as a non-profit

A great source of advice is the Alliance For Justice.

Other Foundations with similar issue focus

Mostly organizations I've become aware of because we grant to the same or similar organizations. Many of these are much larger foundations than this one.

Social Justice Fund Northwest (formerly A Territory Resource)
The Tides Foundation
The Needmor Fund
Third Wave Foundation
Annie E Casey Foundation
Charles Steward Mott Foundation

Foundation Associations

Websites with good information on starting and running foundations and good sources of foundation directories.

Council on Foundations is the national affinity organization.
The Association of Small Foundations offers the Foundation-in-a-Box kit.
Philanthropy Northwest is the regional association that this foundation is a member of.
National Network of Grantmakers - organization of grantmakers with a social justice focus